One of the best videos I’ve seen recently. These guys write a very basic and naive “Network stack” using Swift. They start from scratch, write a few lines of code and then refactor. They repeat the process over and over. The best thing about this video are the comments and reasoning they provide along the process. The end result is a short playground file which you can download and explore (in Swift 2.2). Definitely check this out if you are into learning swift.